What is straw bale gardening?

This alternative form of gardening can add a unique spin to your vegetable or flower gardening.

Yes, these vegetables are growing in a straw bale. (Photo: Grady James/Wikimedia Commons)

Sarah Konradi was searching for an unusual approach to kickstart an interest in vegetable gardening for children in pre-kindergarten programs in Wake County in North Carolina when a friend suggested a novel idea: straw bale gardening.

The concept – think of it as container gardening with a bale of straw as the container – was an immediate success. The goal, said Konradi, a design associate in the Natural Learning Initiative at N.C. State University, was to introduce the 500-plus pre-K children in eight childcare centers to the concept of where healthy food comes from as part of the Initiative's Preventing Obesity by Design program.

Straw bale gardening is an engaging and productive way for home gardeners to add a fun, new dimension to their own gardening experience. The guide below provides an easy, step-by-step approach to straw bale gardening. If you haven't grown veggies in a bale of straw, give it a try. After all, have you ever met a gardener too old to try something new?

Choose the right straw

Be sure you use bales of straw from wheat, oats, rye or barley. With these types of straw, there are virtually no seeds. That's because the "straw" consists of the stalks that remain after the grain has been harvested. They have been through a combine harvester and the seeds have been threshed from them, leaving few if any seeds on the stalk. Hay bales, on the other hand, are made from the whole stalk and therefor have seed heads still on them. Hay bales invariably also include seeds from weeds and grasses.

Find a sunny location

A straw bale looks like it would be a mobile form of gardening – just pick it up and move it where you want it as the sun changes position during the season. Right? Not exactly. When the bale becomes wet, it becomes very heavy. Choose a sunny location where it won't have to be moved once it is set in place. It's a good idea to put several layers of newspaper or cardboard underneath the bale to prevent weeds from growing up into it if you are placing the bale on bare ground or grass. If you place the bale on your patio or deck, you can "dress it up" by putting it inside of a planting frame.

Turn the bale so that the narrow side with the cut straw is facing up. The straw is hollow and the cut ends will allow rain and water from your hose or watering can to enter the straw. This approach is a more effective way to water the straw bale than if the non-cut side, where the straw is folded over, is facing up.

Condition the bale

The bale will begin to decompose as soon as moisture from rain or hand-watering gets on the bale. Decomposition results in heat building up inside the bale, which will "cook" the roots and destroy the plants if the bale has not been properly "conditioned." Conditioning the bale, which takes 10-14 days, prior to planting in it will resolve this problem. While a bale can be conditioned at any time during the year, you can maximize your growing season by beginning the conditioning process two weeks before the earliest planting date in your area. Here's a step-by-step process to condition the bale:

Days 1-3: Water the bale thoroughly so it stays damp.

Days 4-9: Continue watering the bale but add a liquid fertilizer at the strength recommended on the label. This adds nitrogen and will speed the decomposition process.

Day 10: Resume watering without fertilizer. Using a compost or meat thermometer, take the temperature inside the bale. The bale is ready for planting when the interior temperature is the same as the outside temperature. If you take the temperature of the bale during the entire process, you will see the temperature begin to rise after the first few days of watering, spike midway through the process and then start to come back down.

Choosing plants

Almost anything that will grow in an in-ground garden will grow in a bale of straw. Exceptions are tall plants such as indeterminate tomatoes and corn and plants that like to "run," such as sweet potatoes. If you want to grow tomatoes in the bale, choose determinate varieties. The part of the country where you live may affect your choice of plants for this type of gardening. In warm climates, for example, the bale will decompose faster than in cooler climates. Southern gardeners may find that plants that reach maturity quickly or leafy cool-season crops do best in straw bales. Regardless of which plants you choose, space them the same as you would if planting them in the ground.

To create a planting space, form a hole by removing an amount of straw equal to the size of the rootball. Place the plant in the hole, put potting soil around it, and then fill the rest of the hole with some of the straw you removed. Tomatoes should be planted deeper than other plants as tomatoes will form roots along the stems. Water well to settle everything in.

Water and fertilize regularly

Plants grown in a straw bale receive less nutrition from the bale than they would from soil. As a result, you'll need to increase the frequency of fertilizing to every week or two. It's also important to water frequently to keep the bale moist so it doesn't dry out.